Depends on how the array is designed. if it's in a streamlined enclosure, it will have a lesser effect. Also, miniature LED's (the tiny ones on your motherboard and stuff) in a streamlined array might not even affect the rotors at all, because they're maybe 1mm tall? if that?
It's definately a feasable idea, and kind of cool, but the real issue would be, imo, the helicopter itself blocking the image. It'd look funny.